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I have a 1999 Ford F150 that runs great. I keep it maintained as problems arise. It has around 225,000 miles. I now have a problem with the passengers window not working but I know how to fix it and the part is on order, new window regulator/motor. But that is not the issue I’m having. This one I haven’t figured out so I’m looking for help with this one.
I’ll be traveling down the highway with the cruise control on doing 70 miles and hour. No problems until I climb an overpass then the a/c blower slowly stops blowing air. Crest the overpass and the air comes back on. This happens all the time. It won’t do this at ‘around town’ speeds. Since the actuators use vacuum, I looked for a vacuum leak. I repaired a broken vacuum line under the hood a year or so ago.
I’ve been thinking about this for awhile and nothing comes to mind. The alternator had gone bad and replace with a new one, not rebuilt about a year ago. The battery has been replaced recently too. Any ideas?
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things that is coming to my mind is you could be a small abit low on freon… at higher speed it will kick on and off because it will get to low… bascilly Im saying is with the car moving faster the engine will spin faster and the about of time the freon is there would be less before it pushes it to the high sideI would check that with a ac gauge and see what it reads to see if your really low or not. other then a vacuum leak thats all I can think of
I put 2 cans of refrigerant in the truck a couple of months ago, it cools very well. Just the blower slows down and stops when climbing overpasses at speed. Thinking either the actuator is diverting the air flow or the blower itself is somehow not getting power. Just not sure.
I’ve had a chance to think about this answer some more and driven the truck in differrent weather. Seems the weather has a factor as when I first wrote this, the temperature was around 100 degrees or so. We’ve had storms and the temperature has dropped into the 70’s and 80’s and when traveling the same road the blower no longer cuts out when climbing the overpasses. Also the air coming out of the vents are not as cold either.
I would have the battory and alternator tested just in case they are failing… autopart stores do it for free uselly, I would also check the belt and tenchener just incase it has problems like slack, also check the cab filter not just the air intake filter… if you have never replaced the cab filter its probly really dirty aspecialy if anyone smokes in it… check around for vacuum leaks, and ecrctical connections… else it might be your blower motor… or something with it,,, but I would check those others first
I appreciate what you had to say. I’m thinking that there is nothing wrong with the electrical (alternator and battery) simply because the voltmeter is registering about 14 volts and it starts and runs fine. When the alternator had gone bad before the truck would not run well.
I have checked for a cabin air filter on this truck and discovered that it never had a place for one. I did look into having to buy the parts that held the cabin filter and install one but that is way way down on my radar. I do agree at this time that the blower motor may be at fault even though it seems to work fine most all the time with the exception of climbing at speed. As far as the actuator is concerned I’m thinking that there would be a change of air moving from one area to another like to the defroster, I just hear the motor die out during these climbs. I’m just hoping that there may be another explanation I’ve not considered.This is an intermittent problem and happened again yesterday. I had someone with me when it happened and they verified that the air was going to the defroster when going uphill at speed. With that little piece of knowledge, I found someone that fixed it.
Realfixes/realfast has addressed this online so I thought I’d pass this along.
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